Air-conditioning and heating system of a conventional fuel vehicle generally use the waste heat of flue gas or circulating cooling water of the engine as a heating source. However, for a hybrid electric vehicle or a pure electric vehicle, there is no sufficient waste heat for heating of the interior the vehicle. Furthermore, under a condition of extremely low temperature, the heat source is also used to defrost and defog. Thus, an auxiliary electric heating device is needed.
Therefore, an electric heating device using a PTC (Positive Temperature Coefficient) heating assembly is proposed. The electric heating device has a casing and at least one PTC heating assembly disposed inside the casing. The conventional PCT heating assembly includes two electrical insulation plates, a PTC heating element arranged between the two electrical insulation plates and two contact plates (electrode plates). The PCT heater is fixedly clamped by the two contact plates. As the PTC heating assembly includes a plurality of the PTC heating elements, the plurality of the PTC heating elements are difficultly fixed due to different thicknesses or improper arranging positions of the PTC heating elements. Furthermore, because the PTC heating element is very sensitive to the temperature and the heating effects of the plurality of the PTC heating elements are not identical, the plurality of the PTC heating elements may contact each other during heating, thus causing that the plurality of the PTC heating elements can not give full play to their heating performance. In addition, when used in the electric vehicle, the PTC heating element subjects to a high voltage, so that a distance between the two electrode plates is increased in order to avoid arc discharge occurred between the two electrode plates, thus causing the volume and the occupied space of the PTC heating element large.